RECENT WORK IN ACxRICULTURAL SCIENCE. 



AGRICULTURAL CHEMISTRY— AGROTECHNY. 



Annual report on the progress of chemistry for 1910, edited by J. C. Cain 

 and A. J. Greenaway (Ann. Rpts. Prog. Chem. [London'\, 7 {1910), pp. IX+ 

 303). — The contents of this report continuing previous worlv (E. S. R., 23, p. 

 210) are as follows: General and Physical Chemistry, by T. M. Lowry; Inor- 

 ganic Chemistry, by H. B. Baker; Organic Chemistry, by C. H. Desch and A. 

 Lapworth; Analytical Chemistry, by A. R. Ling; Physiological Chemistry, by 

 W. D. Halliburton ; Agricultural Chemistry and Vegetable Physiology, by A. D. 

 Hall; Mineralogical Chemistry, by A. Hutchinson; and Radioactivity, by F. 

 Soddy. 



Yearly report in regard to the progress made in the chemistry of foods 

 and condiments, H. Kuttenkeular {Chem. Ztg., 35 {1911), Nos. 36, pp. 322. 

 323; 38, pp. 338, 339). — A detailed report in regard to the more important work 

 in this direction. 



The chemistry of lime-sulphur wash, W. B. Burgess {Jour. Southeast. Agr. 

 Col. Wye, 1910, No. 19, pp. 61-69). — The proportion of lime to sulphur, accord- 

 ing to the author, should not exceed 1 : 2, and. in general 100 lbs. of lime to 150 

 lbs. of sulphur, or 100 lbs. of lime to 200 lbs. of sulphur should be taken. Lime- 

 sulphur wash when exposed to the air was found to deposit as much as three- 

 fourths of the total sulphur present as free sulphur, the amount deposited, 

 however, depending upon the time of exposure. 



" Lime-sulphur wash as a summer fungicide acts in 2 distinct ways: (1) As a 

 contact spray, the polysulphids in the wash acting in a way similar to liver of 

 sulphur; (2) as a protective coating to the leaves, due to the thin layer of 

 sulphur in a fine state of division deposited, from the thiosulphates and poly- 

 sulphids by decomposition. This sulphur would be much more efficient than 

 flowers of sulphur for 2 reasons : (a) The former adheres very closely to leaves, 

 in fact, can not be removed by the most drastic washing: thus a very great 

 drawback in the use of flowers of sulphur is overcome; (b) owing to its fine 

 state of division, the deposited sulphur would oxidize more quickly than flowers 

 of sulphur, and thus prove a more powerful fungicide, as its action probably 

 depends on the formation of sulphur dioxid. It is probable that the chief value 

 of lime-sulphur wash lies in its use as a means of applying free sulphur to 

 leaves. 



"As to the question of injury, the polysulphids are the most likely to damage 

 the sprayed plant, as liver of sulphur where used too strong is known to cause 

 severe leaf scorching. However, these compounds have been shown above to be 

 very rapidly decomposed, so their injurious action would not be very prolonged. 



" Some preliminary trials with sodium thiosulphate on hop leaves showed 

 that even with 20 per cent solutions only insigniflcant injury was done just at 

 the tip of the leaves, [which] points to the fact that little injury is likely to 

 come from this source," 



405 



